The administration of a preparatory diet containing 150 grams of carbohydrates/day for three days has been used for decades as a standard preparation for an oral glucose tolerance test (OGTT) for the diagnosis of gestational diabetes. The need for a preparatory diet in pregnant women needs to be confirmed. Avoiding the diet will result in simpler administration of the glucose tolerance test. The objective of this study is to determine whether a preparatory diet significantly alters the results of a glucose tolerance test administered to pregnant women. Pregnant women are routinely offered a 1-hour glucose challenge between 24-28 weeks gestation. Women with an abnormal result will compose the study group. A 3-hour oral glucose tolerance test will be administered without a preparatory diet. The patient will then be placed on a standard high carbohydrate diet for 3 days. Foods containing at least 150 mg of carbohydrate will be supplied to the participant, after which the glucose tolerance test will be repeated. Each patient will serve as her own control; the results of the OGTT with and without a preparatory diet will be compared. A pilot study of 20 patients will initially undergo testing. Based on these results, a sample size will be calculated.